Dr. Mai Văn Khiêm at a meeting of the Steering Committee for Flood and Storm Prevention and Control. Photo sggp.org.vn

The weather is changing very erratically and irregularly, while the world faces the crisis of the COVID-19 pandemic. Dr. Mai Văn Khiêm, director of the National Centre of Hydro-Meteorological Forecasting, spoke with Sài Gòn Giải Phóng (Liberated Sài Gòn) newspaper about risks relating to weather to help to avoid the "dual disaster" caused by the pandemic and natural calamities.

How do you assess the natural disasters in Việt Nam in the first months of this year, compared to last year?

In the first months of this year, the natural disasters in our country were not as severe compared to the same period last year.

There were extreme heatwaves on a large scale, but these were less severe than last year.

In the first months of the year, the temperatures across the whole country were higher than the average of many years but the increase in temperature was not as strong as last year.

However, this year, storms were 10-20 days earlier.

Recently, natural disasters have caused many deaths and thousands of people to be displaced. Experts believe that natural disasters are appearing out of season. Why is this?

At present, it is the rainy season in China, so the occurrence of heavy rain is normal and not out of season.

However, the rainfall was more than 600mm in 24 hours, which is considered by the China Meteorological Administration to be the heaviest rainfall in 1,000 years in Henan province.

There was no specific assessment to the cause of this heavy rain, but one of the causes of rare and fierce natural disasters is associated with climate change.

Climate change is considered to change the frequency, intensity, scale, time and patterns of extreme weather and climate phenomenon.

Specifically, the increase of temperature could make the disturbances of the atmospheric system such as the tropical convergence band, vortices, storms, tropical depressions, heavy rains, thunderstorms, and cyclones stronger and more frequent.

In recent years, there have been storms with very strange directions in the East Sea (internationally known as South China Sea), or two and three storms at the same time. Could you explain the phenomenon?

This is due to the activity of The Intertropical Convergence Zone, which is usually formed during the months of the stormy season from June to November every year.

The Intertropical Convergence Zone usually extends for thousands of kilometres, on which there are always low pressure centres, which, if there are favourable conditions, they will strengthen and form storms or tropical depressions.

Forecasting storms operating simultaneously with interacting weather phenomenon is complex and difficult. It requires continuous monitoring to detect small changes in atmospheric circulation.

Currently, the monitoring system in the East Sea and in the Pacific Ocean is still limited and lacks data, thus it is very difficult to forecast storms with complicated directions or that are affected by other storms.

What are the forecasts for winter in the north and the rainy season in the south this year?

As per our forecast, this year, cold weather will arrive early, increasing in frequency and intensity in November, and becoming stronger in December and January 2022.

Due to the cold weather appearing early, the average temperature in November and December in the northern and central regions will be about 0.5 degrees Celsius lower than the average temperature of many previous years. This means that the cold and harmful weather may come earlier than other years.

In terms of the rainy season in southern and Tây Nguyên (Central Highlands) regions, the rainfall in August and September will be 5-15 per cent lower compared to the average, but in October and November, the rainfall in the Tây Nguyên region will be 20-50 per cent higher. The rainfall in the southern region will increase by 10-30 per cent.

In December 2021 and January 2022, out-of-season rain will occur in the two regions.

How should we respond to the 'dual disasters' of the pandemic and extreme weather?

Right now, we need to proactively set up plans to confront the dual effects of the natural disasters and pandemic. The effects of these two disasters is real and alarming. India is an example. The country suffered from the pandemic and Typhoon Tauktae in May this year.

The cumulative consequences of the pandemic and natural disasters will be very dangerous if we do not take the initiative and develop response scenarios. VNS